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author | Erik Lumme <erik@vaadin.com> | 2017-09-13 12:39:49 +0300 |
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committer | Erik Lumme <erik@vaadin.com> | 2017-09-13 12:39:49 +0300 |
commit | 7e21ed054f40a18f43bc715915e9231c9a450cdd (patch) | |
tree | 8a155a3845baa8c1155eed51a2afc1aa2bd4c4ae /documentation/articles | |
parent | aedb9da7cd4d72cf040c430b05e42c49dbc6e2db (diff) | |
download | vaadin-framework-7e21ed054f40a18f43bc715915e9231c9a450cdd.tar.gz vaadin-framework-7e21ed054f40a18f43bc715915e9231c9a450cdd.zip |
Migrate CreatingASimpleComponentContainer
Diffstat (limited to 'documentation/articles')
-rw-r--r-- | documentation/articles/CreatingASimpleComponentContainer.asciidoc | 241 | ||||
-rw-r--r-- | documentation/articles/contents.asciidoc | 1 |
2 files changed, 242 insertions, 0 deletions
diff --git a/documentation/articles/CreatingASimpleComponentContainer.asciidoc b/documentation/articles/CreatingASimpleComponentContainer.asciidoc new file mode 100644 index 0000000000..1d3cb9c372 --- /dev/null +++ b/documentation/articles/CreatingASimpleComponentContainer.asciidoc @@ -0,0 +1,241 @@ +[[creating-a-simple-component-container]] +Creating a simple component container +------------------------------------- + +Components in Vaadin can be roughly split into two groups, `Component`{empty}s +and `ComponentContainer`{empty}s. ComponentContainers are Components in +themselves which can also contain other components. If you are about to +implement a component that contains other components, then you'll get a +headstart by extending Vaadin's `ComponentContainer`. The biggest feature +is in tranferring the list of server side components from your component +to the client. Here's how you do it. + +[[server-side]] +Server Side +^^^^^^^^^^^ + +To start of we implement our server side component. For this we extend +the ready made abstract implementation `AbstractComponentContainer`. This +requires us to implement `addComponent(Component)`, +`removeComponent(Component)`, `replaceComponent(Component, Component)`, +`getComponentCount` and `getComponentIterator()`. + +[source,java] +.... +package com.example.widgetcontainer; + +import java.util.ArrayList; +import java.util.Iterator; +import java.util.List; + +import com.vaadin.ui.AbstractComponentContainer; +import com.vaadin.ui.Component; + +public class WidgetContainer extends AbstractComponentContainer { + + List<Component> children = new ArrayList<Component>(); + + @Override + public void addComponent(Component c) { + children.add(c); + super.addComponent(c); + markAsDirty(); + } + + @Override + public void removeComponent(Component c) { + children.remove(c); + super.removeComponent(c); + markAsDirty(); + } + + public void replaceComponent(Component oldComponent, Component newComponent) { + int index = children.indexOf(oldComponent); + if (index != -1) { + children.remove(index); + children.add(index, newComponent); + fireComponentDetachEvent(oldComponent); + fireComponentAttachEvent(newComponent); + markAsDirty(); + } + } + + public int getComponentCount() { + return children.size(); + } + + public Iterator<Component> iterator() { + return children.iterator(); + } +} +.... + +Add, remove and replace are quite straight forward. In the class we +upkeep a list of children internally, and these three methods modify +them. Add and remove have ready made methods in the super class for +notifying all event handlers that the children have changed and because +of that we should make calls to the super methods after we have updated +the list. In `replaceComponent` we have to call +`fireComponentDetachEvent(Component)` and +`fireComponentAttachEvent(Component)` to manually trigger these events. In +all three methods we should also call `markAsDirty` as a last step to +notify the client side that the children have changed. + +The methods `getComponentCount()` and `iterator()` takes care of providing +the required information that we need to the client side. Here they are +simple delegate methods to the List's `size()` and `iterator()`. + +[[client-side]] +Client Side +^^^^^^^^^^^ + +Next up, we want to set up a standard GWT widget which will be our +component container's client side widget. GWT in itself has a bunch of +component containers in it. In GWT, these are called Panels. For this +case I will start with a `VerticalPanel`. It is roughly the same as +`VerticalLayout` in Vaadin. Down the road you want to edit this file to +add features or even extend Widget to create a complete custom widget. +For now extending `VerticalPanel` is enough and we'll use that as-is. + +[source,java] +.... +package com.example.widgetcontainer.client.ui; + +import com.google.gwt.user.client.ui.VerticalPanel; + +public class VWidgetContainer extends VerticalPanel { + public static final String CLASSNAME = "v-widgetcontainer"; + + public VWidgetContainer() { + setStyleName(CLASSNAME); + } +} +.... + +[[connector]] +Connector +^^^^^^^^^ + +Your widget's Connector will transfer the components from the server +side as child widgets to our widget. The connector will feed the +children to the panel trough it's standard API, namely `add(Widget)`, +`remove(Widget)` and `clear();` + +Instead of going the standard route of extending +`AbstractComponentConnector` as your connector, here we can take use of +Vaadin's internal features and extend +`AbstractComponentContainerConnector`. Additionally to implementing the +`getWidget()` -method from `AbstractComponentConnector`, we also have to +supply the class with an implementation to a method called +`updateCaption(ComponentConnector)`. This method is there if we want the +container to take care of the captions for all the components. We don't +need to take care of these captions in this example so we can leave the +implementation empty. + +The real benefit of extending `AbstractComponentContainerConnector` is +that we can now extend a method called +`onConnectorHierarchyChange(ConnectorHierarchyChangeEvent)`. This method +will be called every time that the server side calls `markAsDirty()` if +the component hierarchy has been changed. From within it, we can call on +`getChildComponents` to get a list of all the child components, and +populate our widget with those. + +[source,java] +.... +package com.example.widgetcontainer.client.ui; + +import java.util.List; + +import com.google.gwt.core.client.GWT; +import com.google.gwt.user.client.ui.Widget; +import com.example.widgetcontainer.WidgetContainer; +import com.vaadin.client.ComponentConnector; +import com.vaadin.client.ConnectorHierarchyChangeEvent; +import com.vaadin.client.ui.AbstractComponentContainerConnector; +import com.vaadin.client.ui.Connect; + +@Connect(WidgetContainer.class) +public class WidgetContainerConnector extends + AbstractComponentContainerConnector { + + @Override + public void onConnectorHierarchyChange(ConnectorHierarchyChangeEvent event) { + List<ComponentConnector> children = getChildComponents(); + VWidgetContainer widget = getWidget(); + widget.clear(); + for (ComponentConnector connector : children) { + widget.add(connector.getWidget()); + } + } + + @Override + public VWidgetContainer getWidget() { + return (VWidgetContainer) super.getWidget(); + } + + public void updateCaption(ComponentConnector connector) { + } +} +.... + +This implementation removes all the component's in the widget and adds +all that are returned from `getChildComponents`. An obvious optimization +to these is to compare what is already in the widget and only +add/remove/move those widgets that have changed. + +[[example-usage]] +Example Usage +^^^^^^^^^^^^^ + +Nothing left but to use the component! Compile the widgetset and check +that the widgetset is in use in your web.xml. Here is a little +stand-alone application that uses this component: + +[source,java] +.... +package com.example.widgetcontainer; + +import java.util.Random; + +import com.vaadin.terminal.WrappedRequest; +import com.vaadin.ui.Button; +import com.vaadin.ui.Button.ClickEvent; +import com.vaadin.ui.Button.ClickListener; +import com.vaadin.ui.CheckBox; +import com.vaadin.ui.Component; +import com.vaadin.ui.Label; +import com.vaadin.ui.UI; + +public class WidgetcontainerUI extends UI { + @Override + public void init(VaadinRequest request) { + VerticalLayout layout = new VerticalLayout(); + layout.setMargin(true); + setContent(layout); + + Label label = new Label("Hello Vaadin user"); + layout.addComponent(label); + final WidgetContainer widgetContainer = new WidgetContainer(); + layout.addComponent(widgetContainer); + widgetContainer.addComponent(new Label( + "Click the button to add components to the WidgetContainer.")); + Button button = new Button("Add more components", new ClickListener() { + @Override + public void buttonClick(ClickEvent event) { + Random randomGenerator = new Random(); + int random = randomGenerator.nextInt(3); + Component component; + if (random % 3 == 0) { + component = new Label("A new label"); + } else if (random % 3 == 1) { + component = new Button("A button!"); + } else { + component = new CheckBox("A textfield"); + } + widgetContainer.addComponent(component); + } + }); + layout.addComponent(button); + } +} +.... diff --git a/documentation/articles/contents.asciidoc b/documentation/articles/contents.asciidoc index 4c5c7f7ca1..c2a1a11316 100644 --- a/documentation/articles/contents.asciidoc +++ b/documentation/articles/contents.asciidoc @@ -76,5 +76,6 @@ are great, too. - link:LabelButtonsExpressively.asciidoc[Label buttons expressively] - link:CreatingAServlet3.0Application.asciidoc[Creating a servlet 3.0 application] - link:CreatingAnEclipseProject.asciidoc[Creating an Eclipse project] +- link:CreatingASimpleComponentContainer.asciidoc[Creating a simple component container] - link:CreatingAUIExtension.asciidoc[Creating a UI extension] - link:CreatingAThemeUsingSass.asciidoc[Creating a theme using Sass] |